Cleaning coolant reservoir tank

[FlaAveo5]

Anyone know how to clean out the coolant reservoir tank? Since I had all the coolant replaced, again, when the timing belt was replaced, the tank looks like crap inside, but has nice clean fluid in it.

What chemicals or what product can I use in it, to get rid of the brownish stains all on the inside, from the old DexCool. I could buy a new tank for $28, would be pretty easy to switch out, but it isn't cracked or anything, so..if it is easy to do...can it be cleaned?

[petrified.rabbit]

You can't clean or replace the tank without draining/changing the coolant again.

Cleaning it would be like cleaning tupperware. I think vinegar or CLR (since you don't eat from it).
Or take it off and run it through our dishwasher.

[FlaAveo5]

Well I tried to take it off, and thats how I broke that brittle wiper motor wire assembly. I took off the 3 tubes, and all the coolant came out of the tank, thats all...from the bigger hose on the underside, not a big deal, I have nearly a full bottle of peak left over from the timing belt replacement.

BUT since I couldnt get the tank all the way out, (it is held in by 3 screws, 2 are simple to get it, the third one is upside-down and right under that canister/motor), you need to be under the car to get it off! GM really designs things easy to fix!! So I just stuck a rag in it and rubbed it around with a few tools, got most of the brown residue out of it, and rinsed it out with hot soapy water, and clear water, then connected it all back up and filled it with Peak, it looks a bit better.

But I wont be buying a new tank, unless it cracks....all because of 1 stupid screw! But I am not going to break my glued on wire harness to have a perfectly clean coolant tank. Just would have been nice to have a clean one with all that clean coolant in it.